1. Field
The present disclosure generally relates to flexible tubing.
2. Description of the Related Art
Many individuals suffer from chronic health problems, the treatment of which requires regular, and sometimes extended, medication deliveries. Certain treatment regimens for diseases such as diabetes, asthma, epilepsy, cancer and even allergies, require the regular delivery of precise amounts of medication for the patient's survival. Treating chronic medical disorders often requires the administration of medication over a long period of time according to a treatment regimen specified by a medical professional, such as a physician.
In cases of patients admitted to a healthcare facility, one or more infusions to be administered to a patient are prescribed by the patient's physician. A pharmacy, generally located within the patient's hospital or healthcare facility, prepares the infusion medication or solution according to the physician's prescription. The pharmacist places the infusion solution in a bag, bottle, syringe, or other container and labels the container. The label typically contains data to identify the patient, physician, medication prescribed, and a control number. The label is generally typed or printed in human readable characters and may also include machine-readable information, such as a bar code that is readable by optical energy or a radio frequency identification (RFID) tag that is readable by radio frequency (RF) energy. The container is transported to the patient's location and a clinician such as a nurse or other health practitioner hangs the container from a rack. The nurse connects a tube between the container and an infusion pumping system and inserts a cannula at the end of the tube into a vein, for an intravenous (IV) infusion, or other part of a patient. The tube may be part of an assembly that includes fittings, connectors, and pumping elements and is frequently referred to as an “IV set.” The pump of the infusion pumping system is started and the infusion proceeds.
Existing infusion pumps include peristaltic pumps that sequentially compress and release segments of a flexible line as well as pumps that manipulate pumping chambers that are incorporated into the IV set. The accuracy of a peristaltic pump is affected by the inner diameter of the tube using in the IV set and flexible tubing having a precise inner diameter is more difficult to produce and therefore more expensive. Similarly, the accuracy of an infusion pump that uses a pumping chamber is dependent upon the accuracy of the size and resilience of the pumping chamber, again leading to a need to produce the disposable IV set in quantities of millions with high accuracy.
IV sets used with peristaltic pumps, currently may use polyvinyl chloride (PVC) as the material is both resilient and provides a good gas barrier. One drawback of PVC, however is that it contains di-ethylhexyl phthalate (DEHP) plasticizer, which tends to leach out into the medical fluid, especially for chemotherapy medications such as Taxol and Taxatere. In order to avoid these chemicals leaching into the medical fluid, IV sets currently use silicone rubber as a resilient element, particularly in a pumping segment that is intended to be placed within the IV pump. One drawback of silicone rubber, however, is that it has a relatively high permeability rate of oxygen and nitrogen transfer, thereby presenting a risk of gas migration from the atmosphere through the tube wall and into the medical fluid. This gas transfer may lead to gas bubbles within the medical fluid, which, if transported through the tube and into the bloodstream of a patient, present a hazard to the patient for air embolism. Certain tubes are provided with coatings intended to provide a gas transmission barrier. Current coating materials include parylene, which is sufficiently rigid that it flakes off when the substrate is repeatedly flexed as occurs in a peristaltic IV pump.